The Symposium provides a fundamental re-evaluation of electron and x-ray microscopy. The time is appropriate for this since an understanding has now been reached about the way electron microscopy of biological materials is seriously constrained by electron beam radiation damage. It is generally believed that electron imaging cannot provide detailed images of the substructure of protein molecules but only images of the residue or "ashes" remaining after extensive ionizing radiation damage. This is a serious blow to biological science, which is almost entirely dependent on the electron microscope in the case of molecules and structures that do not crystallize and so cannot be analyzed by x-ray diffraction. This Symposium considers mainly whether this obstacle can be overcome by use of another type of charged particle which has a more favorable ratio of elastic-to-inelastic cross sections. The Symposium aims to provide a bridge for the communication gap between electron microscope developers and particle physicists. It should be recognized that the current use of electrons for short wavelength microscopy mainly developed because of the ease with which stable electron beams can be generated and not as a result of a selection of particles based on considerations of scattering by light atoms. It is hoped that at this meeting the question of whether an alternative exists can be discussed and finalized. If one is found, it will also discuss, in a preliminary way, how microscopes can be built to utilize this new imaging charged particle. The Symposium will include those few investigators who are using alternative radiations (including x-rays). These investigators will discuss the advantages and disadvantages of their microscopes in comparison with electron microscopes.